Due to space constraints at an application location there is a long felt need to implement an actuator with a plurality of typically selectively and independently controllable plunger units for a respective actuation task with sufficiently compact outer dimensions. This provides on the one hand side sufficient electromagnetic functionality, thus with respect to a required actuation stroke of the plunger units and reaction time or switching time, on the other hand side there is no undesirable mutual mechanical or electromagnetic interference.
It is known in the art to implement actuation functions which require a plurality of actuator units using individual actuator units that are attached or provided independently from each other which typically causes increased configuration or assembly complexity and typically puts limits on the compactness of the entire arrangement.
This problem is aggravated in that the application which requires an engagement of a plurality of plunger units defines that the plunger units have to be closely adjacent to each other and typically may only have a predetermined maximum distance from each other. This, however is typically not solvable with individually attached actuator units or only solve able with limitations.
DE 10 2007 028 600 B4 discloses an electromagnetic actuator where a plurality of for example three actuator units with three corresponding plunger units is provided in a common hollow cylindrical housing. Thus, driving the elongated cylindrical plunger units is provided in that the plunger units contact an engagement surface of a respective associated actuator unit and for example adhere thereto through a magnet effect. Thus, the engagement surface typically forms the distal end of an armature of the respective actuator unit.
Thus, for engagement surfaces of adjacent actuator units which engagement surfaces are driven parallel to each other respective plunger units contact the engagement surfaces of the plunger units with engaging faces of the plunger units in an eccentrical manner which provides a compact arrangement of the plunger units that are run with parallel axes and therefore minimum axial distances of the plunger units from each other can be implemented under the predetermined actuation and installation conditions.
It is a disadvantage of this solution that the eccentrical force impact leads to tilt moments which lead to increased friction and wear and which have to be received by an additional component. Furthermore an actuator is required for actuating each plunger. Actuating the plungers simultaneously unintentionally could lead to an accident.
DE 10 2009 015 486 A1 furthermore discloses to an electromagnetic actuator where a permanent magnet is associated with each actuator pin, wherein the permanent magnets are oriented with opposite polarities and a magnet coil device generates a magnet field through electrical polarity reversal which changes directions with electrical current reversal. Also here force introduction into the actuator pins is performed in an eccentrical manner due to the small installation space.
DE 10 2011 009 327 A1 describes an electromagnetic actuator with eccentrical force application. Permanent magnets are thus associated with a respective pole element.
DE 10 2009 006 061 A1 furthermore discloses an actuator arrangement with two actuators. The actuators are configured as a double actuator respectively including an armature unit and a stator unit. The armature units respective include an actuation pin which is actuatable by spring devices in addition to the magnetic force. Permanent magnets connect the actuation pins with centering elements through a magnetic force.